4.3. Preparing Files for USB Memory Stick Booting

To prepare the USB stick, you will need a system where GNU/Linux is
already running and where USB is supported. With current GNU/Linux systems
the USB stick should be automatically recognized when you insert it. If
it is not you should check that the usb-storage kernel module is loaded.
When the USB stick is inserted, it will be mapped to a device named
/dev/sdX, where the “X” is a letter
in the range a-z. You should be able to see to which device the USB
stick was mapped by running the command dmesg after
inserting it. To write to your stick, you may have to turn off its write
protection switch.

Warning

The procedures described in this section will destroy anything already
on the device! Make very sure that you use the correct device name for
your USB stick. If you use the wrong device the result could be that all
information on for example a hard disk could be lost.

There is an all-in-one file hd-media/boot.img.gz
which contains all the installer files (including the kernel)
.

Note that, although convenient, this method does have one major
disadvantage: the logical size of the device will be limited to 1 GB,
even if the capacity of the USB stick is larger. You will need to
repartition the USB stick and create new file systems to get its full
capacity back if you ever want to use it for some different purpose.

After that, mount the USB memory stick
which will now have
on it, and copy a Debian ISO image (netinst or full CD) to it.
Unmount the stick (umount /mnt) and you are done.

4.3.2. Manually copying files to the USB stick — the flexible way

If you like more flexibility or just want to know what's going on, you
should use the following method to put the files on your stick. One
advantage of using this method is that — if the capacity of your
USB stick is large enough — you have the option of copying a
full CD ISO image to it.